VoIP (Voice-Over-Internet-Protocol) offers a revolutionary way of communication that uses Internet to transfer voices in order to provide conversation over two (or more than two) parties. As technology evolves and Internet in applications of everyday life is more and more pervasive, transmitting voice data using this network backbone and its special Internet Protocol (IP) is not an issue anymore.
In addition, with the pervading of Internet and reduction of relevant cost, acquiring an VoIP phone becomes easier. In Taiwan, since the communication cost over Internet is typically three to five times cheaper than that of using a traditional telephone line, VoIP phone is the best option for saving cost for companies, families and individuals, especially when making long-distance calls.
However, voice quality of the VoIP phones is a technical bottleneck. Since the audio signal of the VoIP phones is compressed, its communication quality depends on the audio encoding/decoding scheme used. The higher the compression ratio, the less bandwidth is required, but the audio quality is compromised such that the quality is not as clear as that of a traditional phone. As a result, notwithstanding the cost of VoIP phone being much cheaper than a traditional phone, VoIP phone lacks a soaring market growth. In light of this, International Telecommunication Union (ITU) has set forth G.723.1 and G.729A standards that provides improvement of the communication quality for VoIP phones. Consequently, the number of people using VoIP phones in recent years has experienced a substantial growth. The VoIP phone market all over the world is increasing. “Financial Times” in British has reported that according to the estimation of a research institute In-Stat/MDR the number of people using the VoIP phones in the U.S. will quickly increase from 0.38 million this year to 4 millions in year local mobile VoIP server 2007.
Nonetheless, a bottleneck in the development of the VoIP phones is still present. Although the VoIP phones offer the possibility of transmission over computer-to-computer, computer-to-phone and phone-to-phone, it is still not capable of providing mobile communication, which greatly limits its popularity in today's world where mobile communication is being pursued.